The biological manifestations of vitamin E deficiency are more protean in various animal species than for any other nutrient. However, man has not been shown conclusively to develop clinical symptoms of vit. E deficiency. Several biochemical and morphological parameters of vit. E deficiency are being evaluated in a group of patients with CF. The patients have uniformly shown decreased plasma alpha-tocopherol. Abnormal erythrocyte hemolysis in vitro has been found in all individuals with less than 400 micron/100 ml alpha-tocopherol. The majority of patients examined thus far have shown excessive excretion of creatine. However, the activities of muscle-derived enzymes have only been occasionally elevated. Subcellular organelles studied by electron microscopy in intestinal biopsies from vit. E deficient patients and controls did not appear to be significantly different. There is evidence in the literature that blood polyamine levels are abnormal in homo- and heterozygotes with cystic fibrosis. Accordingly, these components are being studied in whole blood as well as in the formed elements in blood of cystic fibrosis patients, obligate heterozygotes, and control subjects.